Chair control

ABSTRACT

This invention is a chair control for controlling tilting of a seat in relation to a pedestal or a seat back in relation to a seat or both types of movement. A chair control is frequently sold as a unit to a chair manufacturer for fitting to a pedestal and a seat. The control uses torsion bar restraint against tilting with a single bar providing restraint against both types of tilting. The reaction is taken at the center of the torsion bar at slightly spaced points for separation of the reaction stresses. Two parts of the torsion bar may have different torsional stress characteristics so that one will fail before the other and the occupant will not be likely to be thrown from the seat due to all torsional restraint disappearing at one moment.

United States Patent [72] Inventor Roy Shingler l-larlow, England [21]AppLNo. 753,043 [22 Filed June7,1968 [45] Patented Jams, 1971 [731Assignee Stewart-Warner Limited Harlow, England [54] CHAIR CONTROL 3Clalms, 6 Drnwlng Figs.

[52] U.S.Cl 248/373, 297/301 [51] lnt.Cl. A47c7/00 [50] FleldofSearch297/301, 304, 316, 306, 333, 302,, 3.03; 248/373 [56] References CltedUNlTED STATES PATENTS 2,424,753 7/1947 Herold 297/303 2,633,897 4/1953297/302 2,718,257 9/1955 248/373 2,845,991 8/1958 248/373 2,935,1195/1960 297/304 2,991,125 7/1961 297/304 Primary Examiner- Francis K.Zugel Anorney-Augustus George Douvas ABSTRACT: This invention is a chaircontrol for controlling tilting of a seat in relation to a pedestal or aseat back in relation to a seat or both types of movement. A chaircontrol is frequently sold as a unit to a chair manufacturer for fittingto a pedestal and a seat. The control uses torsion bar restraint againsttilting with a single bar providing restraint against both types oftilting. The reaction is taken at the center of the torsion bar atslightly spaced points for separation of the reaction stresses. Twoparts of the torsion bar may have different torsional stresscharacteristics so that one will fall before the 1 other and theoccupant will not be likely to be thrown from the seat due to alltorsional restraint disappearing at one moment.

PATENTEU JAN 5 SHEET 3 UF 4 PATENTED JAN 5 SHEET k 0F 4 ATTORNEY CHAIRCONTROL This invention relates to a chair control for controllingtilting of a seat in relation to a pedestal or tilting of a seat back inrelation to a seat or both kinds of movement.

Prior art chairs are known in which restraint against tilting isprovided by coil springs and there is also a proposal for a chaircontrol using torsion bar restraint and'in which a torsion bar extendsfrom one side of the chair to the other, one end being keyed to thepedestaland the other end to the seat.

It is an object of the present invention to provide a single torsion bararrangement for providing restraint against tilting of a spider forsecuring to a chair seat in relation to a member for securing to apedestal and against'tilting of a mounting for a seat back in relationto the spider.

A further object of the invention'is to provide torsion bar restraintfor a chair control in which a mounting for securing to part of a seator to a base is coupled near the center of a torsion bar through twomembers spaced apart along the bar by a small distance in relation tothe total length of the bar for separating the reaction stress at thecenter.

A further object of the invention is to provide a torsion bar in twoportions each for providing part of the restraint against tilting, thetwo portions having different torsional deflection characteristics. Thusthey may be of different shapes or different materials or may betreated-differently or may be subjected to different stresses in the,undeflected position. The bars may be two different parts of the lengthof a single bar or i may be two separate bars.

A further object of the present invention is to provide a compact chaircontrol mounting in which a spider for securing to a seat is associatedwith a torsion bar which extends laterally from a member for securing toa pedestal beyond the spider.

The invention may be carried into practice in various ways and twoembodiments will be described by way of example with reference to theaccompanying drawings, of which:

FIG. 1 is a plan view of one half of a symmetrical chair controlembodying the invention;

FIG. la is a bottom plan view of both control; I i

FIG. 2 is an end elevation of the chair control of FIG. 1 showing someof the components inthe undeflected (solid lines) as well as thedeflected (chain lines) position;

FIG. 2a is a partial sectional view taken through the extending end ofthe torsion bar and encircling tube to illustrate the spider arm indeflected position;

FIG. 3is an end view of the pretensioning mechanism; and

FIG. 4 is a view corresponding to FIG. 1 of a modification.

The chair control, which can be sold separately to a chair manufacturer,comprises a pedestal member 11 in the form of a mounting for fasteningto the top'of a chair pedestal, which mounting 11 is welded into a rigidstructure comprising at each side of the centerline 36 arms 12 and 12defining the axis of the torsion bar 13, and also defining the axis of apivot pin 14 serving as a fulcrum for a-tiltable member 15 forsupporting the back of the seat and as an anchorage for the arm 12'.

At each side, a nylon bush 16 is located in a corresponding hole in thearm 12 and has a central square hole in which the correspondingly shapedend of the torsion bar can be keyed. The torsion bar is also keyed in asquare hole in the hardened torque arm 12'. Thus the center portion ofthe torsion bar 13 is keyed in relation to the pedestal member 11.

Spiders 19 for fixing to the under side of the chair seat at either sideof the pedestal comprise metal flange members extending in a fore andaft direction. Each vertical flange has a hole in which is welded ametal tube 21 extending laterally outwards and surrounding the torsionbar 13. A second nylon bush 22 keyed to the torsion bar can turn insidethe tube 21 so that the spider 19 can turn about the center of thetorsion bar as the seat tilts in relation to the pedestal.

At the outer end, the tube 21 is welded to a rigid strap 23 whichcooperates with the end of a screw 24 for adjusting the twist in thetorsion bar in the undeflectedposition of the seat.

halves of the chair The screw 24 is threaded in a nut'23 carried by anarm 26 keyed to the free end 27 of the torsion bar. Also keyed at thisend of the torsion bar is a third nylon bush 28 whose cylindricalsurface can turn inside the end of. the tube 2I. Thus by manuallyadjusting ahandle connected to the screw 24, the outer end of thetorsion bar can be turned in relation to the spider 19 so that restraintagainst initial tilting of the spider in relation to the pedestalmounting 11 can be varied. A similar arm26 at the other side ofthecontrol has a setscrew 37 and lock nut 38 for setting in primarystressduring manufacture or assembly (FIG. 2).

The limits of tilt of the spider 19 are defined respectively by a block31 secured to the under side of the horizontal flange as it makescontact with the pin 14 and by the edge 32 of a circular hole located inthe vertical flange of the spider 19 as that edge makes contact with theunder side'of the pin 14 as can be best seen from FIG. 2.

The back support 15 can turnon four nylon washers 33 mounted on the pin14 as shown best in FIG. 1 and this movement is effected automaticallyas the flange l9 tilts by virtue of a coupling shown generally at 34between the rear end of the spider 19 and the back support member 15.The coupling permits, by provision of an elongated hole for example,some freedom of relative movement to allow for the fact that the spider19 turns about the axis of the torsion bar 13 while the back supportmember 15 turns about the axis of the pin 14' which is laterallydisplaced to the rear. of the bar 13.

However, it will be seen that the restraint against tilting of the seatback is provided by the same torsion bar which provides restraintagainst tilting of the seat The angle of the seat back in theundeflected position can be adjusted by a conventional nut and screwmechanism shown at 35.

A single torsion bar 13 has been described as extending from one side ofthe seat to the other to provide in effect two torsion bars on differentsides of the central axis 36, but it is clear that two separate torsionbars could be provided instead if desired as described below withreference to FIG. 4. In either case one of the bars could be prestressedin the factory to provide some built-in restraint against deflectionfrom the undeflected position of the spiders while adjustment of thetwisting of the other torsion bar can be 'as shown in FIG. I under thecontrol of the user so that he can add to the amount of restraintagainst tilting.

I In this connection an important safety feature is pointed out. In theusual case where the torsion-bar or other spring controlling the chaircontrol eventually breaks, the occupant could be thrown backwards andmay be injured. In the present case it can be arranged that one torsionbar will fail before the other so that when the first bar failsthesecond bar will provide restraint against such ejection from the seatand the occupant can then have the first bar replaced before he uses thechair again.

It is possible to ensure that one bar'fails before the other by havingthem of different materials or shapes by differential prestressing fromopposite ends of the bar, or by having a laminated construction, or byensuring that there is a different torsional stress in each in theundeflected position. Again one bar could be surface treated as byshot-peening or heat treatment so that its fatigue strength will begreater than that of the other. i

It will be seen that the mounting '11 is keyed near the center of thetorsion bar 13 through the arms 12 and 12' and the pin 14, whereas thespiders 19 for mounting the seat are keyed to the ends of the torsionbar at 27. This means that when tilting occurs the two ends of the bartwist in the same sense from the center rather than one end of the bartwisting in relation to the other end.

Also the keying at the center of the bar 13 is by means of the arms 12which are spaced apart by about 2 inches, each arm being about 1 inchfrom the centerof the bar 13. This separates the parts of the stationarypart of the bar I3 where the torsional reaction is taken leaving a deadpart of the bar which will be a little less than 2 inches in length dueto the manufacturing tolerances of the square hole in each arm 12' andthe square section of the bar 13. This arrangement whereby the reactionstresses are separated gives a substantially increased life to the bar.

It will alsobe seen that the mechanism shown in the drawings can be veryquickly modified to be suitable for a single-action chair in which thewhole seat can pivot in relation to the pedestal. Thus it is onlynecessary to remove the seatback fitting l and its linkage at 33 and 34respectively with the pivot pin 14 and the spider 19. In this way astandard fitting can be used for a single-action chair control and, withminor modifications, for a double-action chair control.

FIG. 4 is a modification of FIG. 1 in which the torsion bar 13 isreplaced by two separate torsion bars 41 arranged end to end, and inwhich the control is modified to be for a back action, that is forcontrolling tilting of the seat back in relation to the seat andpedestal.

Similar components have been given the same reference numerals.

It can be seen that the pedestal mounting 11 is in a rigid assembly withthe spiders l9 and the tubes 21 which are keyed at their outer ends tothe outer ends of the torsion bar 41 in a mounting similar to thatalready described. The torsion bars 41 in fact are of circular sectionwith enlarged square ends 42 keyed in the bushes 28 and the arms 26 andlocated axially by washers 43 and screws 44.

At the inner end the back mounting is keyed to the square enlarged end27 of each torsion'bar on either side of the axis. There is thus spacebetween the inner ends of the two torsion bars 41.

Stops limiting tilting are provided by portions 45 of the mounting 15coming into contact with the framework 46 forming part of the pedestalmounting.

I claim:

l. A chair control having a post support member adapted to be carried ona post, the improvement comprising a torsion bar. means fixed to saidpost support'member and fixed to said bar at spaced positions onopposite sides of said post support member for holding said bar againstrotation. at said positions. a pair of spider arms extending rearwardlyfrom the axis of said bar for carrying a seat with eachzspider armspaced adjacent a respective one of said positions,;a: tube for eachspider arm encircling said bar, means securing one end of each tube to arespective one of said spider arms-to prevent relative rotation betweeneach spider arm and the respective tube end, and means securing theopposite end of each-tube independently of the other tube nonrotatablyto a respective end of said bar whereby said bar is stressed separatelybetween each position and a respective end of said bar in response topivotal movement of said spider arms about the axis of said bar with theportion of said bar between said two positions serving to isolate thestresses in one portion of said bar from stresses in the other portionof said bar.

2. The chair control'claimed in claim 1 in which said post support fixedmeans are fixed to saidbar at positions spaced axially of said barsubstantially l inchon opposite sides of the center of said supportmember.

3. ln the chair control claimed in claim 2, a back support, meanspivotally interconnecting said back support and said spider arms alongan axis located rearwardly of said torsion bar, a pivot pin for 'saidback support for ienabling said back support to pivot at a differentangle than said spider arms about an axis located intermediate said barand said rear.- wardly located axis, and means integrally formed on saidmeans fixed to said post support extending rearwardly of said I torsionbar and anchored to said pivot pin at spaced positions.

1. A chair control having a post support member adapted to be carried ona post, the improvement comprising a torsion bar, meaNs fixed to saidpost support member and fixed to said bar at spaced positions onopposite sides of said post support member for holding said bar againstrotation at said positions, a pair of spider arms extending rearwardlyfrom the axis of said bar for carrying a seat with each spider armspaced adjacent a respective one of said positions, a tube for eachspider arm encircling said bar, means securing one end of each tube to arespective one of said spider arms to prevent relative rotation betweeneach spider arm and the respective tube end, and means securing theopposite end of each tube independently of the other tube nonrotatablyto a respective end of said bar whereby said bar is stressed separatelybetween each position and a respective end of said bar in response topivotal movement of said spider arms about the axis of said bar with theportion of said bar between said two positions serving to isolate thestresses in one portion of said bar from stresses in the other portionof said bar.
 2. The chair control claimed in claim 1 in which said postsupport fixed means are fixed to said bar at positions spaced axially ofsaid bar substantially 1 inch on opposite sides of the center of saidsupport member.
 3. In the chair control claimed in claim 2, a backsupport, means pivotally interconnecting said back support and saidspider arms along an axis located rearwardly of said torsion bar, apivot pin for said back support for enabling said back support to pivotat a different angle than said spider arms about an axis locatedintermediate said bar and said rearwardly located axis, and meansintegrally formed on said means fixed to said post support extendingrearwardly of said torsion bar and anchored to said pivot pin at spacedpositions.